The Smart Sensor Simulator (SSS) for the Caterpillar ADEM A3 and ADEM 2000 ECMs (collectively known as an ADEM III) enables investigators to download HVEDR data without risk of spoiling the data by overwriting Snapshot records associated with diagnostic trouble codes. Sometimes information related to the operation of a vehicle at the time of a traffic crash can be found in Caterpillar Snapshot records associated with diagnostic trouble codes. This article provides the operational warnings and technical information regarding the SSS use with the ADEM 3.

Figure 1: A photograph of the Synercon Technologies Smart Sensor Simulator with the 70 pin Caterpillar connectors.

Operational Notes and Warnings

The ADEM III units have large capacitors that may be discharged before being reconnected to power. The key-on signal operates the capacitor charging circuits which may result in an inrush of current. Since the inrush of current is sourced through the SSS, the SSS unit may experience a “brown-out” where the voltage drops in the SSS as the capacitors charge. This results in the SSS microprocessor resetting, which turns off the ignition relay. The symptom of this event is a brief illumination of the green led on the SSS and the cycling of the internal relay. There are 2 remedies for this situation:

  • Use a larger power supply, like a portable jump pack with the 12V cigarette lighter adapter.
  • Continue to cycle the ignition button until the capacitors charge and the relay stays engaged with the green light on. This process does not generate new fault codes.

The SSS-ADEM3 may not create a fault-free environment for ECMs with a 7AS serial number prefixes. For other testing results see the Application Table below.

Some ECM programming and configurations are set to expect certain J1939 messages for information. While the SSS microprocessors generate many commonly used J1939 messages, there may be configurations of ECMs that are looking for J1939 messages that are not provided by the SSS. Some of these configurations can be set by the truck operator which means the factory defaults are not able to identify these changes.

See the TruckCRYPT support for Caterpillar to see what types of data are available from CAT ECMs.

Link to the service notice to add the extra resistors to simulate the sensor needed to measure injector pressure, which is needed for HEUI based engines.

Electronic Control Unit (ECU) Description

The SSS-ADEM III has 2 connectors that are each 70 pins. These connectors are keyed differently, so they cannot be connected incorrectly. The photograph shown below has CAT part numbers for the interfacing connectors.

Figure 2: Caterpillar ADEM III engine control module.

While many ECMs are painted yellow, others may be black or not painted at all. The ECM is located on the driver’s side of the engine, about middle height and towards the rear of the engine compartment.


The Cat ADEM III communicate with service tools and the Forensic Link Adapter using the J1708/J1587 network. This is also known as the ATA protocol in Caterpillar circles. The SSS provides a direct wiring from the ECM to the 9-pin diagnostic connector. The photograph below shows a Smart Sensor Simulator connected to a Cat ADEM III. The diagnostic port has a tool connected. In this case, the tool is a Forensic Link Adapter; however, any diagnostic tool that can use the J1708 network can be used (e.g. Nexiq, Cat Comm Adapter, DPA5, Noregon DLA, etc.).

ECU Applications

A Caterpillar ADEM III form factor ECU is used on engines from 1998 to 2010. While the external shape of the ECM is similar from engine to engine, the internal programming and flash files can be different. Thus, the SSS may not produce the same results on all engines. As such, testing is encouraged to verify the expected operation of the SSS.

The following table shows the different engine configurations that use engine control modules with 70 pins on each connector. The years of production are approximate and are intended to be a guide to identify what engine to expect based on the model year of the truck. The table does not account for discrepancies in model years based on rebuilt engines and glider chassis kits.

If you have an ECM that is not tested, please contact us to discuss some options to verify the expected operation. Many engines are electrically the same but differ in displacement. For example, an MBL engine was tested to be fault free. The MBJ and the MBN engines are likely similar in build and electronics.

Smart Sensor Simulator Design and Programming

The SSS-ADEM 3 uses a Generation 1 printed circuit board that is exclusively licensed from the University of Tulsa. This board uses voltage regulators, resistor networks, digital to analog (DAC) converters, pulse width modulated signals, and J1939 messages to simulate the sensor outputs a truck would provide the engine.

The SSS can accommodate both 2-wire and 4 wire coolant sensors at the same time.

The Accelerator Pedal Position is simulated by sending a 5 volt, 50% duty cycle pulse width modulated signal at approximately 490 Hz. This will register a throttle position of about 51%.

Many vehicles and ECMs expect to see J1939 network traffic. The following messages are generated by the SSS to simulate functions of the truck. The following messages are generated by the CAN channel in the SSS.

PGN Parameter Group Label Period (sec) Source Address CAN ID (Hex) Data
65265 Electronic Brake Controller 1 0.100 11- Brake System Controller 0x18F0010B 00  00  00  00  00  00  00  00
65265 Cruise Control/Vehicle Speed 0.100 23 – Instrument Cluster 0x18FEF117 00  00  00  00  00  00  00  00
65265 Cruise Control/Vehicle Speed 0.100 33 – Body Controller 0x18FEF121 00  00  00  00  00  00  00  00
65265 Cruise Control/Vehicle Speed 0.100 40 – Cab Display 0x18FEF128 00  00  00  00  00  00  00  00
65265 Cruise Control/Vehicle Speed 0.100 49 – Cab Controller 0x18FEF131 00  00  00  00  00  00  00  00
57344 Cab Message 1 1.0 23 – Instrument Cluster 0x18E00017 00  00  00  00  00  00  00  00
57344 Cab Message 1 1.0 33 – Body Controller 0x18E00021 00  00  00  00  00  00  00  00
57344 Cab Message 1 1.0 40 – Cab Display 0x18E00028 00  00  00  00  00  00  00  00
57344 Cab Message 1 1.0 49 – Cab Controller 0x18E00031 00  00  00  00  00  00  00  00
65264 Power Takeoff Information 0.100 23 – Instrument Cluster 0x18FEF017 00  00  00  00  00  00  00  00
65264 Power Takeoff Information 0.100 33 – Body Controller 0x18FEF021 00  00  00  00  00  00  00  00
65264 Power Takeoff Information 0.100 40 – Cab Display 0x18FEF028 00  00  00  00  00  00  00  00
65264 Power Takeoff Information 0.100 49 – Cab Controller 0x18FEF031 00  00  00  00  00  00  00  00


The J1939 messages are sent from 5 source addresses. Four of the sources send duplicate information, which ensures that the ECM sees the messages relaying information in the J1939 messages. The truck operator can change the source address for different messages using CAT ET. Therefore the SSS broadcasts messages from all source addresses, providing the most complete truck simulation environment. For example, the Diesel Particulate Filter regeneration switch status is broadcast on the Cab Message (PGN 57344), but depending on the implementation, the message could come from the Instrument Cluster, Body Controller, Cab Display, or Cab Controller. By broadcasting these messages from all four source addresses, the ECM will be satisfied, regardless of its configuration.

Smart Sensor Simulator Wiring Harness

Matching the programming running on the circuit board to the ADEM A3 ECM requires building a cable interface. The cable is defined by specifying each end of the wires. These signals and circuits are specified in the following table.

CAT Vehicle Connector P1 (P/N: 160-7689)
Vehicle connector Wire Application Color PCB Designator Mini-Fit Jr Rev 7c
P1-2 +5V supply Red/White 5V Veh Supp J18:18
P1-3 Sensor Return Black/White Vehicle Sens Ret J18:8
P1-8 J1708 + Pink J1708 + J18:14
P1-9 J1708 – Purple J1708 – J18:15
P1-10 Output #2 Purple/White Free Free
P1-11 Output #5 Tan/Black Free Free
P1-12 Output #3 Blue/White Free Free
P1-13 Output #4 White/Black Free Free
P1-19 Output # 6 Yellow/Black Vout E J18:6
P1-20 Output # 7 Green/White Vout F J18:7
P1-26 Coolant level Norm Brown/White Vout G J18:2
P1-32 VSS + Blue VSS + J18:4
P1-33 VSS – White VSS – J18:5
P1-34 CAN Low Green J1939 – J18:17
P1-48 ECM power Red Safe 12V J18:1
P1-50 CAN Hi Yellow J1939 + J18:16
P1-54 Coolant level Low Brown V2WS 1 J18:12
P1-63 ECM Ground Black GND J18:9
P1-66 Throttle position Tan PWM 3 J18:11
P1-70 Ignition Orange Ignition J18:10



CAT Engine Connector P2 (P/N: 160-7690)
Engine connector Wire Application Color PCB Designator Mini-Fit Jr Rev 7c
P2-2 +5V supply Red 5V Eng Supply J24:13
P2-3 Return Black Eng Sens Ret J24:12
P2-8 Coolant Solenoid Tan/Black E2WS 1 J24:5
P2-13 Air inlet shutoff Brown VR0 J24:15
P2-14 Barometric Pressure White PWM 2 J24:24
P2-16 Fuel Pressure 1 Blue VR2 J24:10
P2-17 Fuel pressure 2 Purple/White VR1 J24:9
P2-24 Oil Pressure Red/White Vout C J24:21
P2-25 Intake Act Press Pink VR0 J24:14
P2-31 Intake Valve Press Tan E2WS 2 J24:6
P2-32 Engine Coolant Temp Green Vout D J24:22
P2-33 Fuel Temp Yellow Vout A J24:19
P2-35 Intake Man Air Temp Purple Vout B J24:20
P2-40 Boost Press Orange PWM 1 J24:23
P2-48 Engine speed + Brown/White Free Free
P2-49 Engine speed – Green/White Free Free
P2-58 Engine Speed 2+ Yellow/Black Vout H J18:3
P2-59 Engine Speed 2- Black/White Free Free


Free wires are run to enable future use and are not connected internally in the SSS.

All SSS-ADEM3 units shipped after June 28, 2015 also have a wiring modification that enables a circuit to simulate the injector actuation pressure sensor. Instructions for the June 2015 modification are printed as a PDF file.


ACERT   Advanced Combustion Emissions Reduction Technology

ADEM    Advanced Digital Engine Management

CGI         Clean Gas Induction

CRS        Cat Regeneration System

EUI         Electronic Unit Injection

HEUI      Hydraulically actuated and Electronically controlled Unit Injectors

ECM       Electronic Control Module or Engine Control Module

IAPCV    Injection Actuation Pressure Control Valve on HEUI engines only

PGN – J1939 Parameter Group Number